3D models
In 3D, re-entrant wave form rotating scroll waves. As in 2D, these can
be stable or unstable. The image below shows re-entry in a 3D slab of
tissue, which represents a section taken from the heart wall. A scroll
wave rotates around a filament of phase singularity, which is shown in
the image below as a purple tube.

Whole ventricle simulations offer insights into the behaviour of
re-entrant waves and filaments in realistic cardiac geometry. The movie
below shows re-entry and filaments in an anatomically detailed model of
rabbit ventricles that was kindly made available by colleagues at USCD.